I reviewed four new science books for The New York Times. They span millions of years, beginning with the birth of humanity and ending with a serious look at AI. 

I Cook, Therefore I Am. How dropping food in fire made us human. Slate

WHY is it that 20th-century physicists could ask some of the most grandiose questions in science, but if a researcher wondered aloud where language came from, the response was derisive at best. Not only can you not answer the question, they were told, you shouldn't even ask... New Scientist

Between 135,000 and 70,000 years ago, the east African climate was highly unstable and subject to megadroughts. In the worst droughts, Lake Malawi had less than 15% of the water it has today. Crucially, around 70,000 years ago, the climate changed and became wetter and more stable. Surely it's no coincidence that this is when the human species underwent a rapid expansion and began to leave the continent to eventually colonize the rest of the world. PNAS.

The discovery of a jawbone and skull from two ancient hominids by mother and daughter team Maeve and Louise Leakey suggest that the human family tree may need rewriting. Unearthed in Kenya, the remains of Homo habilis and Homo erectus indicate that the two lived side-by-side in Africa for at least half a million years. Previously it was thought that they lived one after the other, Whether H. erectus evolved from H. habilis or whether they each arose from a common ancestor is yet to be discovered. National Geographic.

The difference between the hulking heads of our Neanderthal cousins and our more graceful selves is merely a matter of chance, say scientists in the Journal of Human Evolution. The difference between our skulls and theirs probably results from genetic drift--meaning that our head shape was not selected by nature or in any sense 'intended' but only accidentally came to be. At least we got the nice skulls... the authors of the study say, "Neandertal and modern human crania may simply represent two outcomes from a vast space of random evolutionary possibilities." Anthropology.net, Science Direct/Journal of Human Evolution.

Modern humans originated in Sub-saharan Africa, and from there spread all over the globe. Cambridge scientists, who published their study today in Nature, used genetic information combined with the measurements of 6000 skulls from collections all over the world in order to confirm what's known as the 'Out of Africa' theory. The idea of African origins for humans has become very widely accepted over the last ten or so years--this new study deals a final blow to scholars hanging onto the notion that humans may have originated in separate locations all over the world. SciAM.

Late last month, German archeologists announced the discovery of intricate figurines that were made around 35,000 years ago. Made from mammoth ivory, the beautiful carvings include a mammoth and a lion. Recall from June 27's post--the oldest human jewelery/artwork has been dated to 82,000 years ago. These 35,000-year-old animals, the mammoth especially, look like they might have been made yesterday.

Twenty-seven thousand years ago, a human parent or parents buried their ten-month-old twins. They decorated their babies with red ochre and jewellery, and sheltered them under the shoulder blade of a mammoth. The huge animal scapula protected the infants, and their well-preserved remains were uncovered in Austria in 2005. (Another child was buried nearby). I recently came across this piece about the sad pair in Scientific American, written in 2006. Live Science has good pictures. The find was originally reported in Nature.